KR20040053775A - Miniaturized tact switch - Google Patents

Abstract

PURPOSE: A small tact switch is provided to simplify a manufacturing process, to reduce a manufacturing cost, and to achieve a small size tact switch. CONSTITUTION: A small tact switch comprises a base having a terminal pattern; a contact mounted on the terminal of the base; a stem provided on the contact to push down the contact; and a cover for fixing the stem to the base. The base includes a conductive terminal, and a base main body(22). The conductive terminal is formed by cutting a plurality of lead frames having a constant pattern terminal through a press process of a flat conductive sheet. The base main body is formed integrally with the conductive terminal.

Description

Mini Tact Switch {MINIATURIZED TACT SWITCH}

The present invention relates to a tact switch, and more particularly, to a small tact switch used in a communication and information processing device such as a mobile communication terminal and a PDA.

Small tact switches are used to deposit electrical conductors or electrical contacts or terminals between terminals by pressing and releasing a conductor elastic contact (also called a "metal dome") on a substrate on which a pattern of terminals is formed. Such a small tact switch is provided below the keypad of a mobile phone terminal such that the user repeatedly presses and releases a key of the keypad once to interrupt the electrical signal or power between terminals. In recent years, as the portable communication and information processing devices such as mobile communication terminals and PDAs become smaller and lighter, the size of the tact switch used here is also required to be reduced.

Conventionally, a small tact switch having a size of about 4 mm × 4 mm × 1 mm is used to make a terminal pattern printed circuit board (PCB) that continuously prints the same pattern of switch terminals on an epoxy substrate or a phenol substrate (primarily an epoxy substrate). After coating the remaining portion except the pattern portion with an insulator, a contact was placed on the terminal pattern to cover with a dust cover, and the bonded PCB was bonded to each contact unit.

The conventional small tact switch made by the above-described method has the following problems and needs to be improved.

First, the conventional small tact switch has a problem that the manufacturing cost is too expensive. The high manufacturing cost is due to the excessive processing cost in each process and the complexity of the process itself. However, in particular, the substrate itself is too expensive for epoxy substrates.

Second, the conventional small tact switch has a problem that it is difficult to form the outer terminal. The tact switch must be mounted on another printed circuit board (PCB) as a surface mount component (SMD), wherein a terminal that connects the other printed circuit board (PCB) and the tact switch to each other (this is referred to as an “outer terminal” in the present specification). ) Is required. The conventional small tact switch prints the contact terminal pattern on the upper surface of the substrate, prints the outer terminal on the lower surface of the substrate, and then drills a hole in the substrate to solder the contact terminal pattern and the outer terminal of the substrate. Connected. This method of forming the outer terminals was also a factor in reducing the productivity because the process is too complicated.

Third, a conventional tact is formed by forming multiple tact switch arrays by successively forming the same terminal pattern on a phenol or epoxy substrate, and then cutting each unit tact switch by using a saw or the like. Switch manufacturing methods and structures have limitations in reducing tact switch size. Especially in the case of epoxy, the material itself is not easy to cut, and when the tact switch width is about 2 mm, the cutting loss part is large and irregular, so that it is difficult to cut itself to small size.

Fourth, the tact switch using a phenol or epoxy substrate not only causes harmful problems such as generation of glass dust in the manufacturing process, but also causes environmental problems such as the inability to recycle the substrate and releasing harmful gases upon disposal.

The present invention devised to solve the above problems is to provide a small tact switch having a structure that can be manufactured with a simple process and low manufacturing cost.

Another object of the present invention is to provide a small tact switch having a structure capable of easily manufacturing a contact terminal and an outer terminal for connecting a printed circuit board (PCB).

It is still another object of the present invention to provide a tact switch with an extremely compact structure.

Still another object of the present invention is to provide a tact switch of a material which is not only harmful in the production process and disposal, but is also recyclable without fear of environmental pollution.

1A and 1B are perspective views of a lead frame used in the production of the small tact switch according to the present invention.

2A and 2B are perspective views of an injection molded product having a base body formed by injecting a synthetic resin into a terminal portion of a lead frame shown in FIGS. 1A and 1B.

3A is a perspective view of the unit base cut out from the injection molding shown in FIG. 2A.

3B is a top view of FIG. 3A.

4 is an exploded perspective view of a small tact switch according to the present invention.

5 is an assembled perspective view of the small tact switch according to the present invention.

Explanation of symbols on the main parts of the drawings

10: lead frame 12, 14, 16, 18: terminal

20: base 22: base body

24: contact portion 26: fastening portion

28: cover fastening part 30: contact

36 dust cover 40 stem

42: knob 44: locking jaw

46: pressing protrusion 50: cover

52: center opening 54: flange

56 side opening 58 fastening wing

An object of the present invention described above is a base having a terminal pattern, a contact disposed on an upper surface of a terminal of the base, a stem provided above the contact to receive the contact, and the stem of the base. A small tact switch composed of a cover fixed to the base, the base

A conductor terminal press-processed into a flat sheet of conductor and cut and separated from a lead frame in which a plurality of terminals of a predetermined pattern are continuously formed;

The base frame is formed by injecting a thermoplastic synthetic resin into the terminal portion of the lead frame while inserting the lead frame into a mold, and formed integrally with the conductor terminal.

The base body is preferably molded by injection using LCP (Liquid Crystal Polymer) or PVC (PVC: Polyvinyl Chloride), but the material is not necessarily limited thereto.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Figures 1a and 1b is a perspective view of a lead frame used in the production of a small tact switch according to the present invention, Figures 2a and 2b is formed by injecting a synthetic resin in the terminal portion of the lead frame shown in Figures 1a and 1b 3A is a perspective view of the unit base cut out from the injection molding shown in FIG. 2A, and FIG. 3B is a plan view of FIG. 3A, respectively. The small tact switch according to the present invention may be manufactured in the form of having a dust cover to prevent dust on the top of the contact (see reference numeral 30 in FIG. 4), or may be manufactured in the form of having no dust cover. Can be.

For convenience of explanation, hereinafter, a small tact switch in the case of having a dust cover will be described.

Referring to FIGS. 1A and 1B, a feature of the present invention is that the contact-side terminals 12 and 14 and the outer terminals 16 and 18 are integrally preformed with a lead using a plate-shaped conductive metal sheet. After the frame (lead frame) 10 is made, it is used as a terminal pattern of the tact switch. By doing so, the contact terminals 12 and 14 on which the contacts (see 30 in FIG. 4) are placed and the outer terminals connected to the printed circuit board PCB are integrally formed at one time.

The present invention relates to a small switch of about 4mm x 2mm x 2mm size. 1A and 1B are enlarged by more than 10 times for convenience, but the distance between the terminals of the contact terminals 12 and 14 and the width of the terminals are very narrow, about 0.3 mm. Such a fine terminal pattern can be obtained by pressing a thin metal sheet.

Referring again to FIGS. 1A and 1B, a plurality of terminal patterns are formed in one lead frame, the number of which corresponds to the number of cavities of the mold. In addition, the shape of the terminal pattern formed in the lead frame can be changed in various ways according to the structure of the tact switch. That is, the shape of the terminal pattern shown in FIG. 1A or 1B is merely exemplary.

2A and 2B show that the mold base body 22 is injection molded by inserting the lead frame 10 shown in FIGS. 1A and 1B. In the process of opening and closing the mold once, as many tact switch bases 20 as the number of terminal patterns are produced. The material of the mold base body 22 used at this time is preferably a thermoplastic resin such as LCP (Liquid Crystal Polymer), PVC (PVC: Polyvinyl Chloride), but is not necessarily limited thereto. In addition to being inexpensive, having excellent insulation and durability, other materials that can be recycled without concern for environmental pollution can be selected. When the tact switch base 22 is injected as described above, it is possible to obtain a tact switch base much faster and at a lower cost than when the terminal is printed on the substrate and then cut.

The individual base 20 shown in FIG. 3A is obtained by cutting the C line which is the cutting line in FIG. 2A or 2B and then bending the outer terminal. In FIG. 1A, FIG. 1B, FIG. 2A, or FIG. 2B, line C is a cutting line for separating the unit base 20 from the injection molding. Since the cutting of the metal sheet is easily accomplished by punching, there is no difficulty as in the cutting of the substrate according to the prior art.

3A, 3B, and 4, the base 20 according to the exemplary embodiment of the present invention has a concave in which a contact may be deposited on an upper surface of the base body 22 having a rectangular parallelepiped shape of about 4 mm × 2 mm × 2 mm. A contact stack 24 having a space formed thereon, a contact side first terminal 12 and a second terminal 14 formed parallel to each other at the bottom of the contact stack and protruding below the base body 22; And an outer first terminal 16 and a second terminal 18 integrated with the contact side first terminal 12 and the second terminal 14, respectively, on the left and right sides of the contact accumulator 24. Inserted into the side opening (56) formed in the (50) is formed by removing the fastening protrusions 26 and the base body 22 front lower portion to the cover 50 and the base body 22 combined, and cover 50 The fastening blade 58 of the) is bent is composed of a cover fastening portion 28 that can be seated.

When the dust cover is provided as described above, in forming the upper surface of the base body 22, as shown in FIG. 3A or FIG. 4, the contact is greater than that of the fastening protrusion 26 forming surface 25. The height of the outer circumferential surface 23 of the loading part 24 is made lower. This is to float the dust cover 36 on top of the contact 30 as shown in FIG. 4. In more detail, after the contacts are deposited on the contact stacks 24 of each of the base bodies 22, a plurality of them are collected and arranged in succession, and a long along the outer circumferential surface 23 of the contact stacks 24 of each base body. After attaching a strip-shaped dust cover at a time, the strip-shaped dust cover is cut into individual units according to the width of each base body to form a dust cover 36 on the contact of each tact switch. . Since the dust cover 36 is not necessarily required, when the dust cover 36 is not closed, the fastening protrusion forming surface 25 and the contact housing outer peripheral surface 23 of the base body are molded to the same height.

The base 20 constructed as described above is arranged like the exploded perspective view shown in FIG. 4 with the contact 30, the stem 40 and the cover 50 and assembled as shown in FIG. 5. The dust cover 36 is selectively placed on the contact 30.

The contact is made by coating a metal having high conductivity such as silver on a high elastic metal thin film such as stainless, and then punching it into a press in a form that can be restored upward by pressing and releasing. As shown in FIG. 4, in the present invention, the rectangular metal thin film is divided into three gradations of one central portion 32 and two side portions 32 along the longitudinal direction, so that only the central portion 32 forms a dome shape. Use contacts. This is to keep the elastic force of the contact as it is small while the tact switch is extremely miniaturized and correspondingly the size of the contact. The planar area of the contact used for the base 20 of the size described above is about 2.7 mm x 1.4 mm.

Referring to FIG. 4, since the contact 30 having such a fine structure cannot be operated by the user by pressing the contact finger, the pressing protrusion 46 that can directly press the contact 30 is formed at the bottom thereof. And a stem 40 having a knob formed at an upper end thereof above the contact 30. The stem is injection molded from an insulator synthetic resin.

The base body 22, the contact 30 and the stem 40 are assembled by a cover 50 which receives and engages them. The cover 50 is made by punching a metal plate that can be planarly coincided with the base with a press, a central opening 52 into which a knob 42 of the stem 40 is inserted and protruding at the center thereof. A flange 54 extending downward from four corners so as to cover the upper four sides of the base body 22, the flange 54 extends downward from both sides of the flange to be bent and fastened to the cover fastening portion 58 of the base. It consists of a fastening wing 58 and the side opening 56 which can be assembled by inserting the fastening protrusion 26 of the base. In particular, when the nickel silver copper is used as the material of the cover 50, soldering is possible without plating the material itself, so that the plating process can be omitted, and the cover 50 having excellent quality can be obtained.

5 shows a state in which the base 20, the contact 30, the dust cover 36, the stem 40, and the cover 50 are assembled.

As mentioned above, although the preferred embodiment of the tact switch which concerns on this invention was described with reference to drawings, it does not intend to limit the protection scope of this invention to this, It is the right to all the embodiments equal to or equivalent to the matter of a claim. Should be interpreted as affecting.

According to the present invention, not only the tact switch can be made to a fine size, but also can be manufactured by an easy process, thereby reducing the cost of producing a small tact switch.

Claims (6)

A base having a terminal pattern formed thereon, a contact disposed on an upper surface of the terminal of the base, a stem provided above the contact to receive the contact, and a cover fixing the stem to the base. In the small tact switch consisting of, the base is A conductor terminal press-processed into a sheet-like conductor sheet and cut and separated from a lead frame in which a plurality of terminals having a predetermined pattern are continuously formed; and And a base body formed by injecting a thermoplastic synthetic resin into a terminal portion of the lead frame while inserting the lead frame into a mold and integrally formed with the conductor terminal. The method of claim 1, The base body may include a contact placing portion having a concave space in which contacts may be deposited on an upper surface thereof, fastening protrusions provided at left and right sides of the contact placing portion and inserted into side openings formed in the cover to combine the cover and the base body; A small tact switch comprising a cover fastening portion which is formed by removing the base body from the front side downward, and which can be seated by bending the fastening wing of the cover. The method of claim 1, The conductor terminal may be formed to protrude below the contact side first terminal and the second terminal and the base body, which are formed in parallel with each other at the bottom of the contact placing portion, and the contact side first terminal 12 and the second terminal ( A small tact switch, characterized in that it is composed of an outer first terminal (16) and a second terminal (18), each united integrally with 14). The method of claim 2 or 3, In the contact placing portion, a rectangular metal thin film is divided into three center portions of one center portion and two side portions along a length direction, and a contact having a dome shape is deposited only at the center portion, and a contact can be directly pressed in the upper direction of the contact. A small tact switch having an insulator stem having a knob formed at a lower end thereof and a knob formed at an upper end thereof. The method of claim 2 or 3, The base body, the contact and the stem are assembled by a cover 50 for receiving and engaging them, the cover is formed of a metal plate that can be planarly matched with the base, the center of the knob is inserted into A central opening that can protrude, a flange extending downward from four corners to cover the upper four sides of the base body, it is extended long downward from both sides of the flange can be bent and fastened to the cover fastening portion of the base Small tact switch, characterized in that consisting of a side opening that can be assembled by inserting the fastening blade and the fastening protrusion of the base. The method of claim 5, wherein Small cover tact switch, characterized in that the material of the cover (50).